Combination ovens that are capable of cooking using more than one heating source (e.g., convection, steam, microwave/RF, etc.) have been in use for decades. Each cooking source comes with its own distinct set of characteristics. Thus, a combination oven can typically leverage the advantages of each different cooking source to attempt to provide a cooking process that is improved in terms of time and/or quality.
Whether employed in the context of a combination oven, or a microwave/RF oven, any oven that employs RF cooking will likely need to provide a way to ensure that the RF is contained within the oven. Shielding of the majority of the oven cavity and the door does not typically present technical challenges, and leakage through these boundaries is often easily held relatively low. However, the interface between the walls of the oven cavity and the door can be one of the more challenging areas at which leakage prevention mechanisms must be developed. In many countries specific standards are defined to identify the maximum amount of RF leakage that is allowable from the oven.
One mechanism for ensuring that RF leakage is held below applicable standards at this interface is to employ a choke at the interface. The choke is provided to seal RF energy at the interface by providing what is essentially a tuned reflector assembly to keep RF energy in the oven cavity. These chokes are typically constructed based on providing a quarter-wave resonant circuit. More particularly, such chokes often employ uniform width ¼ wavelength (λ) resonant elements. However, given that the architecture of these typical chokes is dependent on uniform ¼ wavelength width dimensions, the width of the choke can become too large for some target frequencies. Accordingly, it may be desirable to achieve an improved design that is not so restricted in terms of its width.